Conjugated linoleic acid (CLA) is a mixture of positional and configurational isomers of octadecadienoic acid, which are naturally occurring substances found in milk and diary products as well as in meats of ruminants.
The term CLA includes the family of positional and configurational isomers of C18:2 fatty acid, more precisely the cis and trans form of 9,11-10,12- and 11,13-octadecadienoic acids.
Many studies reported that synthetic CLA is an effective agent in inhibiting mammary, colon, forestomach, and skin carcinogenesis in experimental models, due to its modulation of lymphocyte and macrophage activities. Recent clinical and in vivo data disclosed novel biological effects of CLA, e.g. the anti-atherogenic and anti-hyperinsulinemic activities.
After having attracted the attention of the international scientific community for its therapeutic properties above, CLA is gaining further consumer acceptance as nutritional supplement as it has been shown that a CLA-enriched diet produces a significant improvement in overall health conditions.
CLA is also known as a slimming agent, whose oral consumption produces a marked decrease of body fat with increase in the lean body mass. The effects of CLA on body fat/lean ratio seem to be due to inhibition of both proliferation and differentiation of preadipocytes, as observed by Brodie A. E. et al. in J. Nutr. 129:602–6 (1999).
The use of CLA in topical composition and cosmetic method for treating skin conditions selected from the group consisting of wrinkling, sagging, photodamaged skin, sensitive skin, dry skin, flaky skin, red skin, irritated skin, itchy skin and age spots, is disclosed in WO0037040.
Topical compositions of zinc salts of CLA for the treatment of skin disorders, such as eczema, psoriasis and dermatitis and so on WO98/17269 discloses. However, the use of zinc salts of CLA is limited to pharmaceutical and dermatological purposes only. Moreover, the poor solubility of the zinc salts of CLA, either in lipophilic and hydrophilic media, significantly decreases the bioavailability of the active ingredient in said topical treatment.